I have a HP 8530w with a Quadro FX 770m. I connected a monitor to the HDMI interface but it was not recognized. Nvidia settings does not list the monitor in the "X server display config" section. The HDMI interface works in Windows XP so I am sure it is activated.
Actually I do not know how to debug this problem because I have no further information (e.g an error msg). The monitor is just not recognized. I also tried to connect a TV and had the same problem. I searched in the forum but did not find any user with the same problem (most of the people only have problems with sound over HDMI).